You don't tell him. Sheesh. You SHOW him. I'm a big believer that how a person kisses is more or less how they're going to have sex. I can learn alot from a woman by how she sucks face -- her rhythms, aggressiveness, and tenderness. Does she bite? Nibble? Gently suckle lips, or touch my face? Is her tongue used to tease and stroke, or does it stampede into my mouth? See... women can be pretty lousy kissers too.
If you want someone to respond to what you want, you first have to show them how you want it. And this doesn't need to be self-esteem withering. Nobody likes to be stopped mid-saliva swap and critiqued. It takes a little patience, tact, and humor, but the only way you can make someone a better kisser is to demonstrate to them what a great kisser can be. How a kiss can pop a champagne cork in your guts, light your nerves like birthday candles, and make your thighs sticky. Lots of people underestimate, or are ignorant about, the power of a disciplined, sloppy, passionate kiss with just enough tongue and just enough hunger. I've known women who could melt glaciers with their mouths.
Show, don't tell. You can do it. I believe in you.